This invention relates generally to agricultural tool bars and deals more specifically with a tool bar having a pair of side wings which fold forwardly to a transport position.
The tool bars of planters and other agricultural implements carry devices such as planter boxes, cultivators, and other tools which are used to work the soil or otherwise treat the field. The implement is typically pulled through the field by a large tractor with the tool bar in an extended operating position wherein it is oriented traverse to the direction of travel of the tractor. It is common for the span of the tool bar to be thirty feet or more since it is desirable to cover as much surface area as possible for each pass of the implement through the field. These lengthy tool bars are usually constructed such that their two side wings can be folded inwardly for transport. In the folded or transport position, the wing sections are parallel to the direction of travel, and the width of the implement is reduced sufficiently to enable it to pass through gates and along narrow roadways. The United States patents to Stufflebeam, et al., U.S. Pat. No. 3,982,773, Kinzenbaw, U.S. Pat. No. 4,117,893 and Pratt, U.S. Pat. No. 4,137,852 exemplify the known prior art relating to tool bars having folding wing sections.
These existing tool bars have been less than satisfactory in a number of respects. The folding mechanisms are characterized by undue complexity which increases the cost and maintenance problems and reduces the reliability of the implement. Manual operations such as unlatching or unpinning the components by hand are often required before the tool bar can be folded or unfolded. The use of caster wheels in these units increases the instability and the safety problems, particularly when furrow openers, minimum tillage coulters or fertilizer openers are used. Existing implements of this type are also characterized by lack of sufficient ground clearance in the transport position and by excessive overall height which decreases their stability and presents additional problems when power lines and other overhead obstacles are encountered. Moreover, the lack of sufficient flexibility in the wing sections causes problems such as lack of uniformity in seed depth during travel over rolling ground and other uneven terrain.
Another undesirable aspect of existing tool bars is their tendency to apply a disproportionate share of the load on the tractor. This increases the strain on the tractor and adds to its power requirements while making it difficult if not impossible to travel through muddy fields. A further shortcoming is caused by the need for the wing support wheels to provide support in the transport position. These wheels are better suited to cooperate with one another in supporting the wings during travel in the extended operating position, and they must be specially constructed if they are to serve also as support wheels during transport. Lengthy extension of the tool bar to the rear in the transport position is also undesirable because it hampers the maneuverability of the unit and increases the safety and stability problems.
Tool bars which employ the draft arms of a three point tractor hitch are limited in the height to which they can be lifted due to limitations in the lifting capability of the draft arms. Consequently, insufficient clearance above the ground sometimes causes problems in the transport position. Also, the three point tractor hitch is unable to adequately hold the implement down and it can sometimes lift up at an inopportune time.
In view of these and other problems, it is apparent that there is a need for an improved folding tool bar for agricultural implements. It is the principal goal of the present invention to meet that need.
More specifically, it is an object of the invention to provide a folding tool bar which is highly stable in both the folded transport position and in the extended operating position. In this regard, it is important to note that caster wheels and the instability problems associated therewith are avoided.
Another object of the invention is to provide, in a tool bar of the character described, a sturdy axle structure which is substantially centered beneath the folded wing sections in the transport position to reduce the load on the tractor. As a result, muddy ground can be traversed and the tractor can easily pull the implement over even the roughest terrain.
Still another object of the invention is to provide a tool bar of the character described which is maintained well above the ground in the transport position and yet presents a low profile.
A further object of the invention is to provide a tool bar of the character described having a sturdy main beam which wholly supports the wing sections in the transport position of the implement. Accordingly, the wheels of the wing sections need not be specially constructed since they serve only to provide support in the extended operating position of the tool bar.
An additional object to the invention is to provide a tool bar of the character described in which the opposed wing sections have sufficient flexibility to compensate for hilly ground and other uneven field conditions. The seed depth is thus uniform even when planting is carried out on sloping or uneven field contours.
Yet another object of the invention is to provide a tool bar of the character described which is adapted for connection to a standard draw bar and which includes a simple yet reliable mechanism for raising the wing sections off of the ground and for folding and unfolding them. It is a significant feature of the invention that all operations, including folding and unfolding of the tool bar, can be accomplished from the operator's seat of the tractor.
A still further object of the invention is to provide a tool bar of the character described which is simple and economical to construct and operate and which folds forwardly to avoid extending unduly to the rear in its transport position.
Other and further objects of the invention together with the features of novelty appurtenant thereto, will appear in the course of the following description.